Experimental investigation of the shear flow zone in torsional members

In this study an attempt was made to examine experimentally the shear flow zone in reinforced concrete members subjected to pure torsion. The strain distribution through the shear flow zone was measured using a special concrete-embeddable strain gage units that were especially developed for this purpose. The performance and the reliability of the embeddable units were assessed experimentally prior to their application. The units were used to measure the shear flow zone in four full-size beams. It was found that the actual shear zone is smaller than the prediction of the ACI 318-95. The strain distribution through this zone was rather parabolic [sic] which indicated that reinforcement can affect the strain distribution. A rational definition of the shear flow centerline was introduced. Furthermore, discripancy with tests results were discussed. The ACI 318-95 formula for predicting the cracking torque was assessed and found to underestimate the cracking torque, a more accurate approach was proposed. Finally, an attempt was made to investigate the softening of diagonals concrete under torsion --Abstract, page iii

Assessment of Existing Structures Using Cyclic Load Testing

When a building is renovated for a change of use, the load-carrying capacity of the structural system must be established. The cyclic load test (CLT) method requires the application of multiple cycles of loading and unloading (typically six). Two case studies are presented. In both of the described cases, the CLT method efficiently verified the capacities of the existing structures. The method was also used to evaluate structural behavior after members were strengthened using externally bonded fiber-reinforced polymer reinforcement alone or in conjunction with a reinforced concrete topping course

Strengthening of a Reinforced Concrete Bridge with Externally Bonded Steel Reinforced Polymer (SRP)

This paper introduces steel reinforced polymer (SRP) as a way to strengthen civil structures. This technique consists of cords formed by interwoven high-strength steel wires embedded within a polymeric resin. A comprehensive study addressing analysis, design, installation, load rating and monitoring of a bridge strengthened with this technology is reported. The SRP system was easily installed, demonstrating its similarity to more traditional fiber reinforced polymer (FRP) strengthening techniques. Load tests were performed to evaluate the bridge structural behavior prior and after the strengthening in accordance with AASHTO specifications, showing that the rehabilitation performed as predicted and therefore created the possibility to remove the bridge load posting

Characterization of RC Beams Strengthened by Steel Reinforced Polymer and Grout (SRP & SRG) Composites

The use of externally bonded steel reinforced polymer (SRP) and steel reinforced grout (SRG) is a promising new technology for increasing flexural, compressive, and shear capacities of reinforced concrete (RC) members. The flexural performance of RC beams with externally bonded SRP and SRG has been investigated experimentally using four-point bending. The material constants for single-ply SRP and SRG were experimentally determined from coupon tensile tests and torsion tests. Analytical models based on the first-order and higher-order shear deformation theories have been developed to predict the behavior of the retrofitted RC beams. Comparisons between the analytical models and the experimental results show a good correlation for the midspan deflection until the reinforcing steel reaches the plastic region